Research On Several Key Problems In EMC Expert System Of UAV

Many electromagnetic compatibility (EMC) design methods cannot be applied on unmanned aerial vehicle (UAV) for volume, weight and power restrictions of airborne equipments. And there is no existing standard or design criterion of UAV to follow. Therefore, the EMC pre-research task of UAV was advanced, which included research on EMC expert system of UAV. Based on characteristics of EMC of UAV, author analyses several important problems in EMC expert system of UAV.Firstly,the theory foundation of national military standard is analyzed, which is the basis of whole EMC design of UAV. It is propitious to national military standard tailoring and application by fully understanding the meaning and rationality of each item and limit in national military standard.Then, a novel sub-system EMC test method-rule of six test method was raised. This new method can save a lot of testing time and expenses.The real electromagnetic (EM) environment effects on unmanned aerial vehicle is analyzed. And the max harmful outside word EM environment level to UAV is gained after many electromagnetic compatibility tests in darkroom and in actual flying field, which is 60-200V/m in 0.1-8×103MHz bandwidth. The EMC standard at the system level of UAV is advanced as 160dBμV/m-100dBμV/m in 0.1-2×103MHz bandwidth after analyzing the combined effects of conducted and radiated interferences based on the common EM radiated and conducted characteristics of UAV. The standard can provide an effective evacuating rule for EMC of UAV.According to the dipole model, the correlation coefficients of different testing conditions were calculated. The coefficients will help to improve the precision of EMC test.Based on EMC design manual and experiences from UAV experts, many effective EMC design method of UAV were summarized. Adopting these methods at the beginning of design can reduce radiation, enhance EMC of system, shorten design period and cut down design outlays. Subsequently, based on the requirement of EMC expert system of UAV, several novel and effective algorithmic methods were proposed. These methods can help designers to analyze and prognosticate various aspects of EMC design of UAV.(1)The mathematics model of EM interference between airborne antennas was established. The error of this model is normally less than 2%.(2)A calculation method of distance between lines of complicated circuit structure was put forward. The error of this method will not exceed 9% even at large values.(3)Based on distribution method, a novel method to predict the radiation of printed circuit board(PCB) was present. The calculation result is very close to the real test result, which proves the accuracy of this method.(4)A higher order finite-difference time-domain (FDTD) algorithm based on which based on non-standard curvilinear operator was introduce to resolve EMC problems in complex material structure. It can be seen from the calculation results this higher order FDTD method highly improves accuracy and significantly suppresses the artificial dispersion errors. And this method can also save 85% consumption of central processing unit (CPU) and memories approximately.Finally, the perspective of EMC expert system of UAV is proposed. The expert system is trying to simulate the thinking process of real EMC experts without requirements for abundant experiences of designers. Only the basic structure and resolvents of some key problems are mentioned, along with several main algorithmic methods.